When is the best time to plant a tree? 

hong kong wall trees

Forbes Street, 科士街, Kennedy Town, Hong Kong
(Photo Courtesy FORZ)

Twenty years ago.

When is the second best time to plant a tree? 

Right now.

So the saying goes and with the world’s population increasingly urbanized, conserving, protecting and propagating urban greenery and urban forests is vitally important.

Hong Kong is one of the most densly populated sections of the planet. With approximately 18,176 people per square mile it is easy to understand why there might not be enough room for trees in what has become a concrete jungle.

And so, the “wall trees” of Hong Kong have become not only vital for the quality of life in the former British colony but also a unique draw for travelers to the city.

Wall trees are massive beings, generally Chinese banyans (with red-stemmed Fig additions), that have grown on top of and into the cracks of the masonry walls the British government created to develop the steeply sloping hills of Hong Kong island in the 19th and 20th Century.  Think of it like massive terracing projects for urban development.  The banyan is a tenacious species, with its seeds deposited in the stony cracks of the terraces by birds or wind.

Besides just wearing the hat of writer and photographer, I’ve worked for several years part-time as a Permaculture consultant to individuals and organizations seeking to green urban spaces via the creation of “food forests” and other tree-centric (!) strategies and I’m on the board of the North American Green Infrastructure Foundation. This work has taken me to Vancouver, India and Haiti among other places.  When I travel, urban areas with trees are high on my ‘to visit’ list.

The idea of growing trees directly into walls supposedly originated with Guangdong Masonry workers known as the Wu Hua in the 1800’s.  But in general it is thought that most of the 1,200 wall trees alive today took root by themselves.

The wall trees help stabilize the soil, soak up and transpirate the large amounts of water accumulated behind the terraces (thus alleviating pressure on the stone-work), filter particulate pollution and deflecting heat pollution from both cars and building-wide air conditioning units. As the trees have grown they have further stabilized the walls and offered relieving shade to the residents of the city.

hong kong

Forbes Street, 科士街, Kennedy Town, Hong Kong
(Photo courtesy KennethTom).

These amazing trees can be found all over Hong Kong island with some of the more notable stands along Kennedy Road, Forbes Street (near the playground), Bonham Road (including the tallest one in the city), by the former police headquarters on Hollywood Road, St. Stephens Lane, and by the Mid-Levels escalator on Robinson Road.

Other must see trees and stands can be found on Ship Street in Wan Chaim on Queen’s Road East, behind the Hom Shing Temple in Wan Chai, at Stubbs Road Park in Wan Chai, on Bowen Road and Wan Chai Gap Road in Wan Chai and at the Lung Chu Street Nullah in Sham Shui Po.

These trees are not only of great ecological value to the city but they have also grown to be part of the cultural landscape of the city, garnering conservation efforts from nearby residents, many who feel that the trees create better Feng Shui and from many others who simply remember what it was like to be a child under the protection of great trees.

The opportunity of more of these trees to root is small because the new retaining walls being constructed today are made of reinforced concrete, meaning that no new trees will be growing in them so the protection of existing stands is vital.

The challenge for Hong Kong is how to preserve these trees and the environments they create as they age and reach the end of their lifespan.  Because the local government does not consider tree nor urban forest environments as “monuments” they are not protected. However the walls themselves could be protected as monuments.

Jim Chi-yung of the University of Hong Kong told the South China Morning Post that the walls and their trees are “world-class urban living heritage” and that  “People don’t realize what kind of treasure they possess and it’s a pity people don’t think they are valuable. There’s a great need to raise awareness of this heritage. We should create statutory laws to protect them and teach people in schools what heritage is really about.”

On your next visit to Hong Kong, take a look at these beauties and do your part to protect them by telling the local government how the wall trees impacted your visit.





  1. Comment by Maria Elena Gonzalez Henriquez

    Maria Elena Gonzalez Henriquez Reply October 26, 2012 at 2:09 pm

    WOW! this is really interesting….I like it so much…the planet needs more green….

  2. Comment by Steve Collins

    Steve Collins Reply October 26, 2012 at 3:36 pm

    Amazing! I'm surprised that the trees don't undermine the walls.

  3. Comment by Marc d'Entremont

    Marc d'Entremont Reply October 27, 2012 at 11:55 pm

    I'm sure the trees will undermine the wall, but it shows nature's primacy.

  4. Comment by fotoeins | henry

    fotoeins | henry Reply October 28, 2012 at 3:36 am

    I remembered seeing these in my month in Hong Kong. I completely forgot to look them up; so, I’m glad I’ve come across your post about the wall trees. They’re definitely an interesting counterpoint to the wholly urban environment that is Hong Kong.

    • Comment by Jim O'Donnell

      Jim O'Donnell Reply October 28, 2012 at 10:02 pm

      Henry, I’ve studied these trees and the impacts around them for several years but I have sadly never seen them. Hong Kong is WAY high up on my list of places to visit and I cant wait to see these trees! I think the people of HK…and all urban areas…would see a dramatic improval in the quality of life if they would just integrate trees into the city-scape.

  5. Comment by Lisbeth Larsen

    Lisbeth Larsen Reply October 30, 2012 at 2:26 pm

    Completely amazing – but let us hope those roots don't undermine the wall eventually!

    • Comment by Jim O'Donnell

      Jim O'Donnell Reply November 21, 2012 at 1:10 am

      I agree, they are amazing. From what I've read Lisbeth, the roots dont undermine the old walls because there is plenty of soil for them to access. The new walls may be another story however since they are cement with no soil fill. A crack in the cement could easily host a tree that could cause some problems.

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